Ozone layer depletion and its control measures

Ozone layer is a thin blanket-like layer that spreads over the atmosphere of the earth.The ozone layer protects the surface of the earth and its phenomena from stray rays from the sun.It allows only the required doses of the Sun’s solar energy to reach the earth’s surface.Man has tried hard to deploy protective measures towards controlling the ozone layer from depletion,but this is so impossible to be achieved with the rapid growth of industries.Most factories release untreated effluents to the atmosphere which may be held in the atmosphere or react with other atoms to cause a great effect to the ozone layer with time.

Energy from the sun reaches the earth as infra-red,visible and ultra-violet(U.V) light.Among these forms of light from the sun,it is ultra-violet rays that are biologically proven as harmful beyond certain doses.This UV light can be classified in to three categories,namely:Ultra violet light type A(UV-A),ultra violet light type B(UV-B) and ultra violet light type C(UV-C).The wavelengh for UV-A ranges between 320 and 400 nanometers(nm).UV-B has the wavelength ranging from 290 and 320 nm.And finally,the wavelength of UV-C ranges between 190 and 290nm.Among these UV radiation categories,only UV-A and UV-B reaches the surface of the earth,where as UV-C is absorbed before it reaches the atmosphere,therefore it is the only harmless UV light rays to the earth and its occupants. Depletion of ozone layer has led to increased solar ultra violet(UV-B) radiation at earth’s surface.The ultra violet radiation is readily absorbed by living tissue,and since light at this wavelength has sufficient energy to break chemical bonds,it can be injurious to both plants,animals and human beings.
Effects of ozone layer depletion to human beings include:(i)Skin deterioration:This effect is not life-threatening since it only affects the outermost layer of the skin,hence affecting appearence.It is the most harmless effect of excess solar radiation as a result of ozone layer depletion.(ii)Skin cancer.There exist two main forms of skin cancer,namely: melanoma and non-melanoma.Melanoma is the most serious form of skin cancer.It’s often fatal.Non-melanoma is the most common form of skin cancer which damages the skin’s DNA. It has low fatality rate.(iii)Sun-evoked rash.(iv)Immune inhibition.(v)Cataracts.It accounts for the major causes of blindness in the world.Though surgery in developed countries has been success.

Effects of ozone layer depletion to plants include:Affects the physiological and developmental processes of plants such as yields,leaf size,photosynthesis rate,and resistance to diseases and insects.

Effects of ozone layer depletion to marine ecosystems:Planktons only respond to visible light energy but not ultra violet form of light.Planktons refer to the collection of micro-organisms that live in the water bodies including oceans,seas,lakes,ponds,among others.These are classfied into two types,namely Phytoplanktons and zooplanktons.Phytoplanktons are actually micro-organic plants,where as zooplanktons are micro-organic animals.Exposure of these planktons to excessive solar radiation,of course due to ozone layer depletion,their survival rates are drastically minimised.Early developmental phases of marine animals including fish becomes damaged.Larval development becomes impaired, and reproductive capacity becomes reduced.

Effects of ozone layer depletion to biogeochemical cycles:Excessive ultra violet rays reaching the earth’s surface alters the sources and sinks of greenhouses gases as well as chemically important trace gases such as carbondioxide,ozone and carbonmonoxide gases.

Effects of ozone layer depletion to other materials:Ultra violet rays especially type B(UV-B) affects synthetic polymers and some other materials.This limits the length of time for which they are useful outdoors.
The following are various causes of ozone layer depletion,an effect that has led to high rate of side effects to the earth’s surface as well as living things including human beings.(i)Chlorofluorocarbons(CFCs).Chlorofluorocarbons or CFCs are non-toxic and non-flammable. They contain fluorine atoms, carbon atoms and chlorine atoms. Man-made CFCs are the main cause of stratospheric ozone depletion. CFCs have a lifetime of about 50 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time. Although emissions of CFCs around the developed world have largely ceased due to international control agreements, the damage to the stratospheric ozone layer will continue for a number of years to come.The 5 main CFCs include trichlorofluoromethane ,dichloro-difluoromethane,trichloro-trifluoroethane ,dichloro-tetrfluoroethane and chloropentafluoroethane.

CFCs have been widely used as coolants in refrigeration and air conditioners, as solvents in cleaners, particularly for electronic circuit boards, as a blowing agents in the production of foam e.g. fire extinguishers and as propellants in aerosols. CFCs persists in the atmosphere long enough to diffuse upward into the stratosphere.Intense heat radiation from the sun breaks them up,releasing reactive chlorine atoms which destroy the ozone layer.These chlorine atoms are usually regenerated by various reactions in the atmosphere.For this reason,the atoms are capable of reacting with ozone layer over and over again.Whilst chlorine is a natural threat to ozone, CFCs which contain chlorine are a man-made problem. Although CFC molecules are several times heavier than air, winds mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight. CFCs are insoluble in water and relatively unreactive in the lower atmosphere but are quickly mixed and reach the stratosphere regardless of their weight. When UV radiation hits a CFC molecule it causes one chlorine atom to break away. The chlorine atom then hits an ozone molecule consisting of three oxygen atoms and takes one of the oxygen molecules, destroying the ozone molecule and turning it into oxygen. When an oxygen molecule hits the molecule of chlorine monoxide, the two oxygen atoms join and form an oxygen molecule. When this happens, the chlorine atom is free and can continue to destroy ozone. 

(ii)Man-made halocarbon refregerators.Halocarbon is a generic term covering a number of human-produced gases all containing carbon and halogen.Examples of these halogen gases include:fluorine, chlorine or bromine atoms. Halocarbons include chlorofluocarbons (CFCs) and halons. The halocarnons were widely used for a variety of purposes such as propellants in aerosol cans. in the manufacture of soft and hard foams, in refrigeration and air conditioning, and as cleaning solvents. Consequently, they were increasing rapidly in the atmosphere.Halocarbons in the troposphere are inert, non-toxic. non-flammable,odourless and colourless. However, when they reach the stratosphere, particularly at and above the layer of maximum ozone, high-energy ultraviolet photons from the sun heats the halogenic carbons to free chlorine or bromine atoms. These atoms catalytically detach one oxygen atom from an ozone molecule, thus convert ozone to molecular oxygen,hence depleting the ozone layer.

(iii)Other ozone layer depleting substances include: Propellants and solvents;Ozone depleting chemicals such as carbon tetrachloride and trichloethane;Nitric oxide,chlorine radical and bromine radical.
Prevention of ozone layer depletion effects: Measures have been taken by various countries to phase down the use of CFCs, as well as other ozone depleting chemicals such as halons and other man-made halocarbons.Day-to-day activities that may help reduce the effects of excess solar radiation include:Seeking shade,wearing protective clothing,and sun glasses, using sunscreens: creams that repair uv-induced DNA damage,substances applied topically to the skin or eaten in the diet that protect against some of the detrimental effects of sun exposure.


Categories of telecommunication antennas

An antenna can be defined as an electromagnetic radiator that converts electromagnetic wave into electrical signals,as well as converting electrical signals into electromagnetic waves.Antennas are means of coupling the transmitter to the medium(free space).
The origin of antennas dates back  in the mid  1800s.Since then much evolution has occurred . A  major  advancement was propagated by Guglielmo Marconi  who set up  a  wireless  call that traveled  to  boats across  the  Atlantic  Ocean. Previous  to  this radio  transitions had  a very  limited  range such  that houses  very  close could  talk  to  each  other, but communication  over  great distances was unlikely to occur. The next  breakthrough  was  around 1920s  when  operators at Radio  Arlington  were  able  to  transmit the  sound of  a human  voice up  and  down  the Atlantic  coast. With this advancement in antenna communication,it was considered a major  breakthrough  and  the beginning  of Amplitude  Modulation radio. Radio  waves  are similar  to  light  waves but  vary in  some aspects.  Whereas light waves always follow  the inverse  square law ,the radio waves do not.  There  are  many  external  conditions that affect  a radio  wave such  as atmospheric conditions. Discovery of  radio signals  as electromagnetic  waves is  attributed  to Heinrich  Hertz.   In  radio applications there  is a  radiated  field that  leaves  the conductor  and travels through space. Antennas create a series  of  oscillation  waves with specified  frequencies and wavelengths. The electromagnetic  wave travels  away  from  the antenna up  to a  distance  where the  energy  is  completely damped  by  the environment.  
Antennas exhibit the following properties: 1.Gain,2.polarization,3. direction and 4.aperture.

1.Gain is a measure of increase in power.An antenna with higher gain is more effective in its radiation pattern.Antennas are designed such that power raises in wanted direction and decreases in unwanted direction. As the gain of antenna increases,the angle of radiation reduces hence increasing coverage distance.This is why omnidirectional antennas are considered low-gain antennas whereas directional antennas are considered high-gain antennas.

2.Direction is the shape of the transmission pattern.The directivity of an antenna is considered as the capability of an antenna to radiate signal power to a given direction.

3.Polarization.An electromagnetic Wave may be polarized vertically or horizontally. Combination of both vertical and horizontal polarization results to  circular polarization.

4.Aperture can be said to be a collective area of an antenna that actively takes part in transmission and reception of electromagnetic waves.
Antennas can be classified in three broad categories:Omni-directional,directional and semi directional.

Omni-directional antennas propagate wave signals in all directions i.e at an angle of 360°.They are considered low-gain antennas(LGAs) with high bandwidth, therefore can propagate in all directions regardless of terrain.Their application is mainly in spacecraft where they are used as a backup to high gain antennas(HGAs).Omnidirectional antennas include; dipole antenna.
Directional antennas refer to the high-gain antennas that radiate or receive high radio signal power in a speficific direction,hence improving performance and reducing interference.They have a narrow beam that make their propagation highly directional.Directional antennas include;Parabolic/dish antenna,helical antenna,quad antenna,billboard antenna,log periodic antenna and yagi antenna.They offer enhanced performance in some directions at the expense of other directions.
Semi directional antennas propagate at a specific angle.Semi-directional antennas include; Patch,panel and yagi antenna.
After having looked at the three broad categories of antennas,let’s now look at the various types of antennas.I have already named them under the categories above.They include;

1.Parabolic antennas.Also known as dish reflector.A parabolic reflector has a high degree of directivity,hence has a high ability to focus radio frequency waves in to a narrow beam.Beamwidth is <25°.It converts diverging spherical wavefront into parallel wavefront that produces a narrow beam of the antenna.They are mainly used for long distance communication links over large geographical areas.

2. Helical/helix antenna.A simple structure made up of wire(s) wound to form a helix.The most common design is a single wire backed by the ground and fed with coaxial line.

3.Yagi antenna.It’s actually Yagi-Udah Array,named after its founders,Shintaro Uda and Hidetsugu Yagi.Can be constructed with one or more reflector and director elements. It uses several dipoles(reflector and director elements) to form a directional array.They have a beam-width of between 30° and 80°.A dipole propagates radio frequency (RF) energy,then the immediate dipoles reradiate the RF energy in phase and out of phase respectively.

4.Patch antenna.A semi directional antenna that uses a flat metal strip mounted above a ground plane.Forward directionality is enhanced since radiation from the back is cut off by the ground plane.It can have a beamwidth of between 30° and 180°.

 5.Log periodic antenna.It is made of a series of dipoles placed along the antenna axis at different space intervals of time followed by a logarithmic function of frequency .Mainly used in wide range of applications where variable bandwidth is required alongside antenna gain and directivity. Some of its versions are bow-tie and logperiodic dipole array.Bowtie antenna,also known as butterfly antenna, resembles a bowtie.Logperiodic dipole is mainly used in wireless communication technology.

6.Dipole antennas.Consists of two thin metal rods with a sinusoidal voltage difference between them.They are very simple to construct and use.They are the most common omnidirectional antenna used.They propagate a radio frequency energy of 360° in the horizontal plane.Consists of two metallic rods through which current and frequency flow.Its other versions include;short dipole, monopole and loop antenna.

7.Grid antennas.To prevent dish reflectors from moving out of alignment or deforming due to high wind conditions,the parabolic antenna can be perforated to form grid antenna with square meshes or simply grids.It’s gain and beamwidth are similar to that of dish/parabolic antenna.

Importance and Categories of phones

A mobile phone is a hand-held device that allows communication between two people.The mobile is indeed a type of computer.From the definition of the term computer,a computer is an electronic device that accepts data,manipulates or processes that data,and transmits it in to a meaningful information understandable by end users.On the other hand,a mobile phone contains all the parts of a desktop and a laptop,though its parts are somehow fused.For instance, the CPU,screen and keypad are fused,as opposed to desktop where the parts are separate; the CPU is contained in the system unit,keyboard and monitor/screen are connected to the system unit as separate peripheral devices.
Mobile phones started being developed as from 1980s.The phases of development can be classified into 5 generations.i)First generation of mobile telephony(1G):1G was introduced inthe 1980s.The main technology used in 1G phones was AMPS(Advanced Mobile Phone System).Mutiple access mode used was FDMA(Frequency Division Multiple Access).The phones had no access to the internet.Their battery life was very short, and they were prone to background interference.ii)Second generation of mobile telephony(2G):This generation of mobile phones was developed around 1994.The main technology used was GSM(Global System for Mobile).Multiple address mode employed were TDMA(Time Division Multiple Access) and CDMA(Code Division Multiple Access).The phones had access to a narrowband internetwork.The network range was low,and data rates were slow.iii)Third generation of mobile telephony(3G):3G development began in 2001.WCDMA was the technology used.CDMA was used as a multiple access mode.Broadband internet network coverage was accessible.The phones had high security compared to the preceding ones.This generation still faced the problem of low network coverage.High power consumption was also realised.iv)Fourth generation of mobile telephony(4G):Developed in 2009.Technologies used include LTE and WiMAX.Multiple addressing mode was also CDMA.Internet service was ultrabroadband.Their speed was high.v)Fifth generation of mobile telephony(5G).This is the current generation still under development.It will apply artificial intelligence technology.
The mobile phones posses many functions apart from making and receiving calls.It allows text messaging where different people can send each other instant messages.It offers internet services too,nowadays phones can access internet and allow users to interact with search engines including yahoo,Google and hot mail; access social media platforms such as Facebook,twitter,instagram,telegram,google+,palmchat,whatsapp,hi-5,LinkedIn,etc;to interact with entertainment sites like tubidy.com,YouTube and waptrick.com to download and livestream music,video and various kinds of multimedia.The phone offers photography services too;it has camera for taking photos and videos which are saved in the phone’s memory for future reference.Phones also play a very important role in money transfer and banking services.The sim card can enable the used send and receive money to and from other users.For instance,safaricom users enjoy   M-PESA services.M-banking is also an emerging issue in mobile phone development, Banks are nowadays integrated with mobile phones to offer banking services where people can save money and borrow loans.The mobile phone has also a clock,a calender,radio and many other features.
The parts of a mobile phone are divided in to two main categories;external parts and internal parts.External parts are located outside,and they include;external keypad,power switch,screen,earphone socket,charging socket,antenna and casing.The keypad allows input of alphanumerical data and special characters in to the mobile phone.The entry of data is done through typing using fingers.The power switch puts the phone on and off.Putting on is sometimes called booting.This switch is also known as on/off button.The screen,also known as display,is used to display data for user’s viewing.Casing covers the internal parts of the mobile phone,protecting them from external forces that might result to their damage.On the other hand,the internal parts are so many ranging from medium to minute.CPU ,control processing unit,is directly connected to the internal keypad.It controls all the sections of the mobile phone, since it plays a very important role in processing data.That’s why it is sometimes called processor. Earpiece allows conversion of electrical signals to sound signals.From its term,it is the part that is close the ear while making calls.It enables you get what you are told by the other phone user.Mouthpiece on the other hand,is the part that is usually closer to the mouth when making or receiving calls.It allows conversion of sound signals to electrical signals.So what you say is in form of sound,which can only be transmissible after being converted to electrical signals.In simple terms,it transmits sound from one phone to another.Battery, is a source of power for the phone.Power IC is used to supply power to all electronic parts of the phone, from the battery.The oscillator creates frequency during ongoing and outgoing calls.Flash IC stores programs installed in the mobile phone.Charging IC,charges the battery by taking current from the charger.SIM(subscriber identity module) socket or interface is directly connected with the CPU in most mobile phones.In some mobile cell phones,the sim card interface is connected with the CPU through power IC.Battery connector is the part in contact with the battery termianals.Memory card socket or section is found within the CPU.It is where SD cards/memory card is placed.Coil receives sound signals from audio section inbuilt within the CPU.Ringer/buzzer/speaker is connected to the audio amplifier IC to obtain loud sound. Transistor,Diode,LED,Resistor,Capacitor,Regulator and Mic are also internal parts of the mobile cell phone.

Context Management Systems,and founders

According to Wikipedia, they describe a CMS as follows:

A web content management system (WCMS or Web CMS) is a content management system (CMS) software, usually implemented as a Web application, for creating and managing HTML content. It is used to manage and control a large, dynamic collection of Web material (HTML documents and their associated images). A CMS facilitates content creation, content control, editing, and many essential Web maintenance functions.

May 18, 2000

Expression Engine to be updated soon to be updated soonRadiant CMS to be updated soon to be updated soonLightCMS to be updated soon to be updated soon


to be updated soon to be updated soon

Cushy CMS

to be updated soon

CMS Founders Year of Launch
WordPress Matt Mullenweg and Mike Little May 27, 2003
Joomla   Mambo  August 17, 2005
Drupal Dries Buytaert
 to be updated soon

The rise of computer games


Computer games  video games played on a personal computer rather than a dedicated video game console .  From the 90s, PC games lost mass-market traction to console games.

Effects of Video Games

Positive effects

1)Video games boosts  the ability to follow instructions

2)It enhances Problem solving and logic – Playing a game such as The Angry Birds, one trains his brain to come up with creative ways to solve puzzles and other problems.

3)It improves Hand-eye coordination,  spatial skills,etc.  The player must coordinate the brain’s interpretation and reaction with the movement in his hands and fingertips.

3)It facilitates quick thinking, making fast analysis and decisions.  Sometimes the player does this almost every second of the game giving the brain a real workout.

4)Promotes Accuracy – Action games, according to a study by the University of Rochester, train the player’s brain to make faster decisions without losing accuracy.

5)It enhances strategy and anticipation –The gamer must deal with immediate problems while keeping his long-term goals on his horizon.

6)It improves situational awareness  Many strategy games require the player to become mindful of sudden situational changes in the game and adapt accordingly.

7)Develops reading and math skills – The  use of  math skills is important to win in many games that involves quantitative analysis like managing resources.

8)Pattern recognition – Most games have internal logic in them, and the player figures it out by recognizing patterns.

9)Taking risks – Winning in any game involves a player’s courage to take risks in most cases.

10)Promotes teamwork and cooperation  – Many multiplayer games such as FIFA involve cooperation with other online players in order to win.

Optical Fibre is A faster communication medium indeed


Fibre optic cables are very fast media of communication.Modern fiber cables can contain up to a thousand fibers in a single cable,with a huge potential bandwidth. They have a much greater bandwidth than other media of ccommunication. The amount of information that can be transmitted per unit time of fibre over other transmission media is its most significant advantage. Not all fibres in the cable may be lit. Optical fibers are very strong, but the strength is drastically reduced by unavoidable microscopic surface flaws inherent in the manufacturing process. The initial fiber strength, as well as its change with time, must be considered relative to the stress imposed on the fiber during handling, cabling, and installation for a given set of environmental conditions.The optical fibres trammit data using light.An optical fibre offers low power loss.  This allows for longer transmission distances.  In comparison to other media it can cover a distance of up to 2000m. Fibre optic cables are immune to electromagnetic interference and radiofrequency interference.  It can also be run in electrically noisy environments without concern as electrical noise will not affect fibre.
Fibre optic cables are much thinner and lighter than metal wires.  They also occupy less space with cables of the same information capacity.  Lighter weight makes fibre easier to install.Since the fibre is a dielectric, it cannot produce sparks in harzadous envirronments.It’s the most secure medium available for carrying sensitive data. An optical fibre has greater tensile strength than copper or steel fibres of the same diameter.  It is flexible, bends easily and resists most corrosive elements that attack copper cable.


Artificial intelligence-the backbone of future machines


Artificial intelligence (AI) is the ability of a computer to think like a human ,it is actually the  intelligence exhibited by machines or software. AI today is properly known as narrow AI , in that it is designed to perform a narrow task e.g. only facial recognition. However, the long-term goal of many researchers is to create general AI (AGI or strong AI). Narrow AI may outperform humans at whatever its specific task is, like playing chess or solving equations, AGI would outperform humans at nearly every cognitive task.The central  goals of AI research include reasoning, knowledge, planning, learning, natural language processing (communication), perception and the ability to move and manipulate objects.. There are a large number of tools used in AI, including versions of search and mathematical optimization, logic, methods based on probability and economics, and many others. The AI field is interdisciplinary, in which a number of sciences and professions converge, including computer science, mathematics , neuroscience,etc .The field was founded on the claim that human intelligence can be so precisely described that a machine can be made to simulate it.  Science fiction often portrays AI as robots with human-like characteristics.The risk may arise when AI succeeds and an AI system becomes better than humans at all cognitive tasks. Such a system could potentially undergo recursive self-improvement leaving human intellect far behind. By inventing revolutionary new technologies, such a superintelligence might help us eradicate war, disease, and poverty, and so the creation of strong AI might be the biggest event in human history.  Experts  believe research today will help better ,prepare for and prevent  potentially negative consequences in the future, thus enjoying the benefits of AI while avoiding pitfalls.Most researchers agree that a superintelligent AI is unlikely to exhibit human emotions like love or hate. Autonomous weapons are artificial intelligence systems that are programmed to kill. In the hands of the wrong person, these weapons could easily cause mass casualties. A super-intelligent AI will be extremely good at accomplishing its goals, and if those goals aren’t aligned with ours, there will be a problem.


Samsung Galaxy Note 4

Samsung Galaxy Note 4 Phablet
This is another great android phone in Kenya from Samsung. As mentioned, Samsung has become a household name in the Kenyans Smartphone market and you can only expect the brand to appear more than once in this list.

Galaxy Note 4 is quite a looker when it comes to physical appearance. Some of the key features that make this phone a great gadget include but not limited to the massive 5.7-inch super AMOLED screen with protective corning Gorilla Glass 3, and an S Pen for taking notes and getting creative.

It runs on highspeed processors with 3GB of RAM. For those who are in love with phone cameras, Galaxy Note 4 features a 16 megapixel camera with optical image stabilization and LED flash. You also get high quality images with the front facing 3.7 megapixel camera. Price: from KSh 61,480.
Where to Buy Galaxy Note 4
Jumia.co.keKSh 61,480.00 View Offer